The proposed investigation will evaluate the effects of systematic changes in the characteristics and conditions of presentation of computer-synthesized speech-like auditory signals on an averaged auditory event-related potential, the frequency following response (FFR). The study is designed to document the spectral and temporal properties of the FFR in normal-hearing listeners evoked by nonspeech and speech-like signal under conditions of monaural presentation in quiet. The electrophysiological measurements will be made using several electrode configurations and will be analyzed using spectral analysis and cross-correlation techniques to determine whether the FFR preserves the spectral cues essential for vowel perception. In addition, we propose to measure the FFR to simple and complex signals in the presence of monaural and binaural masking noise. The data will be analyzed to determine whether the perceptual release from masking observed under selected dichotic conditions (termed masking level differences or MLDs) is reflected in measurements of the FFR. These data will be used to draw inferences regarding the source of neural generation of the FFR.